TWI746079B - Anti-lock braking system and control method - Google Patents

Abstract

An anti-lock braking system and control method are executed after a control module intervenes in the braking system of a vehicle, and receives a wheel speed signal and an acceleration signal of the vehicle; calculates based on the wheel speed signal and the acceleration signal of the vehicle A slip feedback value, and a basic control voltage is generated according to a slip deviation value between a slip target value and the slip feedback value; the slip feedback value is differentially compensated to generate a slip compensation value, The slip compensation value corresponds to a feed-forward voltage in a table look-up method; the basic control voltage is added to the feed-forward voltage to generate a brake control voltage; and the brake control voltage is output to a proportional valve brake. The proportional valve brake adjusts a brake pressure according to the brake control voltage to reduce the wheel speed change when the ABS system intervenes during braking.

Description

Anti-lock braking system and control method

The invention relates to a braking system and method, in particular to an anti-lock braking system and a control method.

Please refer to FIG. 10, the conventional Anti-lock Braking System (ABS) includes a solenoid valve brake module and a control module 30. For example, a vehicle 40 may include a plurality of wheels. For example, it may include a left front wheel 41, a right front wheel 42, a left rear wheel 43, and a right rear wheel 44. Correspondingly, the solenoid valve brake module may include four solenoid valve brakes 31, and the control module 30 is electrically connected The multiple solenoid valve brakes 31 are used to control the multiple solenoid valve brakes 31 to apply braking pressure to the multiple wheels. In addition, the control module 30 is electrically connected to multiple sensors (such as wheel speedometers, accelerometers, etc.) of the vehicle ) To obtain the driving information of the vehicle (such as wheel speed, vehicle speed, acceleration... etc.).

The following briefly describes the conventional control process of the anti-lock braking system (ABS). The control module 30 first determines whether there is a braking event, that is, whether the brake pedal of the vehicle is depressed; when it is determined that there is a braking event, the control The module further determines whether a vehicle dynamics reaches an early warning threshold. For example, the vehicle dynamics can be, for example, the measured wheel deceleration of the wheel, and the early warning threshold is a threshold value of the wheel deceleration. In addition, generally speaking, slip differential refers to the speed difference between the vehicle speed and wheel speed of the vehicle, which can be expressed as follows:

When the slip is too large, it may cause the vehicle 40 to slip on the road. Therefore, when the control module 30 determines that the vehicle dynamics reaches the early warning threshold, the control module 30 actively intervenes in a part of the vehicle 40. The braking system is used to automatically control the solenoid valve braking module. At this time, the braking behavior of the vehicle 40 is controlled by the control module 30, thereby automatically adjusting the slowing speed of each wheel and suppressing the slip state, and avoiding Each of the wheels is locked in order to achieve the effect of stabilizing the vehicle.

After the control module 30 intervenes in the braking system of the vehicle, it drives the solenoid valve brakes 31 to alternately switch between a release state and a braking state. When each solenoid valve brake 31 is operated in the release state, In order to let the brake oil pass through an oil pressure valve to release the pressure, for example, the brake pressure can be zero after the pressure is released; Increase braking pressure. However, the conventional anti-lock braking system still contains the following disadvantages:

1. Each solenoid valve brake 31 is only alternately switched between the release state and the brake state. During the alternate switching process, the oil pressure valve of each solenoid valve brake 31 is subjected to the impact of oil pressure (that is, equivalent to water). Hammer phenomenon), it is easy to cause damage to the solenoid valve brake 31.

2. After the control module 30 intervenes in the braking system of the vehicle 40, each of the solenoid valve brakes 31 only alternately switches between the release state and the braking state. For each wheel, the wheel speed is sudden and unexpected. Therefore, the fluctuation of the wheel speed of each wheel may cause the driver or passenger to experience intermittent rapid vibration in the vehicle, which may cause discomfort.

In view of this, the main purpose of the present invention is to provide an anti-lock braking system and control method, in order to improve the two shortcomings described in the prior art.

The anti-lock braking system of the present invention is provided for a vehicle with a plurality of wheels. The anti-lock braking system includes: an accelerometer, which outputs an acceleration signal, and the acceleration signal reflects the acceleration of the vehicle; multiple wheel speedometers, respectively In response to the plurality of wheels of the vehicle, each of the wheel speedometers respectively outputs a wheel speed signal, and the wheel speed signal reflects the wheel speed of each wheel; The plural proportional valve brakes respectively correspond to the plural wheels of the vehicle, each of the proportional valve brakes receives a brake control voltage, and adjusts a brake pressure of each wheel according to the magnitude of the brake control voltage; and a control module, The accelerometer, the multiple wheel speedometer and the multiple proportional valve brake are electrically connected. After the control module intervenes in a braking system of the vehicle, it is based on the wheel speed signal of each wheel speedometer and the acceleration of the accelerometer The signal generates the braking control voltage of each of the proportional valve brakes; wherein, the control module calculates a slip feedback value according to the wheel speed signal and the acceleration signal of each wheel speedometer, and according to a slip target value and the A slip deviation value between the slip feedback values generates a basic control voltage; the control module performs differential compensation on the slip feedback value to generate a slip compensation value, and compensates the slip by a look-up table The value corresponds to a feedforward voltage; the control module adds the basic control voltage to the feedforward voltage to generate the brake control voltage.

The anti-lock braking control method of the present invention is executed after a control module intervenes in a braking system of a vehicle, the vehicle includes a plurality of wheels, and the anti-lock braking control method includes: receiving a wheel speed signal of each wheel of the vehicle And an acceleration signal; calculate a slip feedback value according to the wheel speed signal and the acceleration signal of the vehicle, and generate a basic control voltage according to a slip deviation value between a slip target value and the slip feedback value ; The slip feedback value is differentially compensated to generate a slip compensation value, and the slip compensation value corresponds to a feedforward voltage in a table look-up mode; the basic control voltage is added to the feedforward voltage to generate a Brake control voltage; and output the brake control voltage to a proportional valve brake, and the proportional valve brake adjusts a brake pressure of each wheel according to the magnitude of the brake control voltage.

Compared with the prior art, the present invention has the following effects:

1. Different from the conventional solenoid valve brakes, the proportional valve brake of the present invention is not like the conventional solenoid valve brakes, which can only alternately switch between the released state and the brake state. The brake pressure of the proportional valve brake changes with the voltage, so the brake pressure can be adjusted more finely, and the oil pressure shock of the oil pressure valve of the proportional valve brake can be effectively alleviated. Compared with the conventional solenoid valve brake, The proportional valve brake of the present invention is less likely to be damaged due to hydraulic shock.

2. The present invention fine-tunes the brake pressure of each proportional valve brake through the brake control voltage. The brake control voltage includes the component of the feedforward voltage. The feedforward voltage can effectively reduce the change of the wheel speed of each wheel, thereby enabling Avoid the experience of intermittent rapid vibration of the driver or passenger in the car, so as not to cause discomfort.

10: Accelerometer

100: acceleration signal

11: Wheel speedometer

110: Wheel speed signal

12: Brake brake module

120: Proportional valve brake

13: Control module

20: Vehicle

21: Left front wheel

22: Right front wheel

23: left rear wheel

24: right rear wheel

30: Control module

31: Solenoid valve brake

40: Vehicle

41: left front wheel

42: right front wheel

43: left rear wheel

44: right rear wheel

V _P : Brake control voltage

Slip _FB : Slip feedback value

Slip _TG : Slip target value

Slip _ERR : slip deviation value

V _B : Basic control voltage

Slip _COMP : slip compensation value

Slip _{COMP_F} : The first slip compensation value

Slip _{COMP_R} : The second slip compensation value

V _FF : Feedforward voltage

V _{FF_F} : the first feedforward voltage

V _{FF_R} : second feedforward voltage

V _est : Vehicle speed

W : Wheel speed

V _{LV_F} : the first lower limit voltage

V _{UV_F} : The first upper limit voltage

S _{L_F} : the lower limit of the first slip

S _{U_F} : the upper limit of the first slip

V _{LV_R} : The second lower limit voltage

V _{UV_R} : The second upper limit voltage

S _{L_R} : The second lower limit of slip

S _{U_R} : The second upper limit of slip

Σ: Sum operation

Figure 1: A block diagram of an embodiment of the anti-lock braking system of the present invention.

Figure 2: A schematic diagram of the anti-lock braking system of the present invention applied to a vehicle.

Fig. 3: A schematic flowchart of an embodiment of an anti-lock braking control method of the present invention.

Fig. 4: The present invention generates the brake control voltage to the proportional valve brake.

Fig. 5: A schematic diagram of the operation of the PID control unit in Fig. 4 in the S-domain.

Fig. 6: A schematic diagram of a first comparison table in an embodiment of the present invention.

Fig. 7: A schematic diagram of a second comparison table in an embodiment of the present invention.

Figure 8A: Waveform diagram of vehicle speed, left front wheel and right front wheel (the brake control voltage does not include the feedforward voltage).

Figure 8B: Waveform diagram of vehicle speed, left rear wheel and right rear wheel (the brake control voltage does not include the feedforward voltage).

Figure 9A: Waveform diagram of vehicle speed, left front wheel and right front wheel (brake control voltage includes feedforward voltage).

Fig. 9B: Waveform diagram of vehicle speed, left rear wheel and right rear wheel (brake control voltage includes feedforward voltage).

Figure 10: A schematic diagram of a conventional anti-lock braking system applied to a vehicle.

Please refer to Figures 1 and 2, an embodiment of the Anti-lock Braking System (ABS) of the present invention includes an accelerometer 10, multiple wheel speedometers 11, a brake module 12 and a control module 13. For example, the anti-lock braking system of the present invention is provided for a vehicle 20 having a plurality of wheels, and the brake module 12 includes a plurality of proportional valve brakes 120 respectively corresponding to the plurality of wheels, each of the proportional valve brakes 120 is used to adjust the braking pressure of each wheel.

Please refer to FIG. 2, the plurality of wheels of the vehicle 20 may include (but are not limited to) a plurality of front wheels and a plurality of rear wheels, the plurality of front wheels may include a left front wheel 21 and a right front wheel 22, and the plurality of rear wheels may include a A left rear wheel 23 and a right rear wheel 24. Correspondingly, the brake module 12 may include four proportional valve brakes 120 to adjust the braking pressure of the left front wheel 21, the right front wheel 22, the left rear wheel 23, and the right rear wheel 24 respectively.

It should be noted that, referring to FIG. 1, the working principles of the accelerometer 10, the multiple wheel speedometer 11, the brake module 12, and the proportional valve brake 120 of the present invention are common knowledge in the technical field. It will not be described in detail here, but will be briefly described as follows. The accelerometer 10 outputs an acceleration signal 100, the acceleration signal 100 reflects the acceleration of the vehicle 20; the plural wheel speedometers 11 respectively correspond to the plural wheels of the vehicle 20, and each wheel speedometer 11 respectively outputs a wheel speed signal 110, The wheel speed signal 110 reflects the wheel speed of each wheel; each of the proportional valve brakes 120 receives a brake control voltage V _P , and adjusts a brake pressure of each wheel according to the magnitude of the brake control voltage V _P. When the brake control voltage V _P is greater, the brake pressure provided by each of the proportional valve brakes 120 is smaller. In other words, to increase the pressure relief degree of each of the proportional valve brakes 120, the voltage value of the brake control voltage V _{P can be increased} ; On the contrary, if you want to control each of the proportional valve brake 120 to increase pressure, you can reduce the voltage value of each of the brake control voltage V _P.

1 and 2, the control module 13 is electrically connected to the accelerometer 10, the plurality of wheel speedometers 11 and the plurality of proportional valve brake 120, the control module 13 according to the wheel speedometer 11 The speed signal 110 and the acceleration signal 100 of the accelerometer 10 generate the braking control voltage V _{P of} each of the proportional valve brakes 120, thereby individually controlling the braking pressure of each wheel. The following description will only control one of the wheels. As an example, the control situation of other wheels can be deduced by analogy. Therefore, as a whole, the left front wheel 21, the right front wheel 22, the left rear wheel 23, and the right rear wheel 24 of the vehicle 20 are independently controlled, so that the braking distance can be effectively shortened and the braking efficiency can be improved.

Please refer to FIGS. 1 to 3 in conjunction. The embodiment of the anti-lock braking control method of the present invention is implemented in the control module 13. It should be noted that the anti-lock braking control method of the present invention is implemented in the control module 13 is implemented after actively intervening in a braking system of the vehicle 20. Like the conventional anti-lock braking system (ABS), the conditions for the control module 13 of the present invention to actively intervene in the braking system are common knowledge in the technical field, and will not be detailed here.

Please refer to FIG. 3 and FIG. 4, the anti-lock braking control method of the present invention includes the following steps:

Step S01: The control module 13 receives the wheel speed signals 110 and the acceleration signals 100 of the wheel speedometers 11. As mentioned above, the wheel speed signal 110 is received from the wheel speedometer 11, which reflects the current wheel speed of each wheel; the acceleration signal 100 is received from the accelerometer 10, which reflects the current wheel speed of the vehicle 20 Acceleration.

Step S02: The control module 13 calculates a slip feedback value Slip _FB according to the wheel speed signal 110 and the acceleration signal 100 of each of the wheel speedometers 11, and according to a slip target value Slip _TG and the slip feedback Slip A slip deviation value Slip _{ERR between the FB} values generates a basic control voltage V _B. In the embodiment of the present invention, the slip feedback value (Slip _FB ) can be expressed as follows:

In the above formula, V _{est is} the vehicle speed of the vehicle 20, and W is the wheel speed of each wheel. Among them, the wheel speed W of each wheel can be expressed as follows:

In the above formula, v _{rpm is} the wheel speed signal 110, v _rpm reflects the number of turns of each wheel in a unit time (per minute), and r is the radius of each wheel (unit: meters).

In the embodiment of the present invention, the vehicle speed V _est is a function including time (t), which can preferably be expressed as follows:

The above formula refers to the public literature of the Society of Automotive Engineers (SAE):

；k表示數據的時間點，例如

(k)表示當下時間點的車速，

(k-1)表示上一時間點的車速；K ₂代表權重，0

K ₂

1；r _est 為各該車輪的半徑；ω(k)為各該車輪的輪速，即W=ω(k)；a _meas 為該車輛20的加速度(即：該加速度信號100)。簡言之，該車輛的車速V _est 為根據該輪速信號110與該加速度信號100所產生的一估計值，藉由權重K ₂的設定，可決定車速V _est 的估算較仰賴各該車輪的輪速W或該車輛20的加速度a _meas 。 in,

; K represents the time point of the data, for example

( k ) represents the vehicle speed at the current point in time,

( k -1) represents the vehicle speed at the previous point in time; K ₂ represents the weight, 0

K ₂

1; r _est is the radius of each wheel; ω ( k ) is the wheel speed of each wheel, namely W = ω ( k ); a _{meas is} the acceleration of the vehicle 20 (that is, the acceleration signal 100). In short, the vehicle speed V _est is an estimated value generated based on the wheel speed signal 110 and the acceleration signal 100. With the setting of the weight K ₂ , it can be determined that the estimation of the vehicle speed V _est depends on the wheel speed. The wheel speed W or the acceleration a _{meas of} the vehicle 20.

The slip target value Slip _TG is a preset value, and its representative meaning is the slip value to be pursued when the brake control is implemented through the present invention. For example, the slip target value Slip _TG can be less than or equal to 20%, but not The limit is 20%. Therefore, the slip deviation value Slip _ERR can be expressed as follows: Slip _ERR = Slip _TG - Slip _FB

The control module 13 generates a basic control voltage V _B through a proportional-integral-derivative (PID) control unit according to the slip deviation value Slip _ERR . The operation of the PID control unit is common knowledge in the technical field, such as using Figure 5 uses the classical control architecture to calculate the minimized error value and send the correction amount, which will not be detailed. Among them, the value range of the proportional gain is preferably between 0 and 5 (including 0 and 5), the value range of the integral gain is preferably between 0 and 1 (including 0 and 1), and the value of the differential gain Preferably, the range can be between 0 and 1 (including 0 and 1).

Step S03: The control module 13 performs differential compensation on the slip feedback value Slip _FB to generate a slip compensation value Slip _COMP , and corresponds the slip compensation value Slip _COMP to a feedforward voltage V in a table look-up manner _FF . In the embodiment of the present invention, the slip compensation value Slip _COMP can be expressed as follows:

C

1，不同的各該車輪所對應的C值不同，舉例來說，該複數前車輪(包含該左前輪21與該右前輪22)的C值大於該複數後車輪(包含該左後輪23與該右後輪24)的C值，較佳的，該複數前車輪的C值可為0.6，該複數後車輪的C值可為0.1，但不以前述數值為限。 In the above formula, C is the weight, 0

C

1, each of the various wheels corresponding to different values of C, for example, the plurality of front wheels (22 21 including the left front wheel and the right front wheel) is greater than the value C of the plurality of wheels (including the rear wheel 23 and the left the right rear wheel 24) of the C value, preferably, the value C of the plurality of front wheels may be 0.6, the value C of the plurality of rear wheels can be 0.1, but are not limited to the foregoing numerical value.

V _FF

10V，而各該比例閥制動器120的操作電壓範圍例如可在3.5V至9V之間(包含3.5V及9V)。當該滑差補償值Slip _COMP 越大，該前饋電壓V _FF 的電壓大小也越大，故該滑差補償值Slip _COMP 與該前饋電壓V _FF 可具有正比比例關係。 Regarding the table look-up method, that is, the control module 13 stores a comparison table, and the comparison table enables a slip compensation value Slip _COMP to correspond to a voltage magnitude of the feedforward voltage V _FF. Generally speaking, the voltage value of the feedforward voltage V _FF is between 0 volts (V) and 10V, that is, 0 V

V _FF

10 V , and the operating voltage range of each of the proportional valve brakes 120 can be, for example, between 3.5V and 9V (including 3.5V and 9V). When the slip compensation value Slip _COMP is larger, the voltage magnitude of the feedforward voltage V _FF is also larger, so the slip compensation value Slip _COMP and the feedforward voltage V _FF may have a proportional relationship.

In the embodiment of the present invention, the control module 13 stores a plurality of comparison tables, including a first comparison table and a second comparison table. The first comparison table corresponds to the plural front wheels, and the second comparison table corresponds to the plural rear wheels. wheel.

Please refer to FIG. 6 to display the data contained in the first comparison table. The details are as follows: calculate from the acceleration signal 100 shown in FIG. 1 and the wheel speed signal 110 of the left front wheel 21 or the right front wheel 22 The obtained slip compensation value Slip _{COMP is} defined as a first slip compensation value Slip _{COMP_F} , and the feedforward voltage V _FF corresponding to the left front wheel 21 and the right front wheel 22 is defined as a first feedforward voltage V _{FF_F} . When the first slip compensation value Slip _{COMP_F} is equal to a first slip lower limit S _{L_F} (for example, 10%), the first feedforward voltage V _{FF_F} corresponds to a first lower limit voltage V _{LV_F} (for example, 5V); when the first slip _slip COMP_F compensation value is equal to a first upper limit value of slip _S U_F (e.g. 60%), which first feedforward voltage _V FF_F equal to one corresponding to the first upper limit voltage _V UV_F (e.g. 10V); When Slip _{COMP_F} < S _{L_F} , the first feedforward voltage V _{FF_F} corresponds to 0V; when S _{L_F} < Slip _{COMP_F} < S _{U_F} , the first slip compensation value Slip _{COMP_F} and the first feedforward voltage V _{FF_F} have a proportional linear relationship to scale, and _{V LV_F <V FF_F <V UV_F} ; when _Slip COMP_F> when _S U_F, the first feed-forward voltage _V FF_F corresponding to the first upper limit is equal to the voltage _V UV_F. Wherein, in order to avoid insufficient pressure relief, the upper limit voltage V _{UV_F} can be set to be greater than a maximum value of the operating voltage range of each of the proportional valve brakes 120, as mentioned above, because the operating voltage range of each of the proportional valve brakes 120 can be within Between 3.5V and 9V, the upper limit voltage V _{UV_F} can be set to 10V.

In the embodiment of the present invention, after the parameter setting of the control module 13, the first comparison table includes the first lower limit voltage V _{LV_F} , the first upper limit voltage V _{UV_F} , and the first slip lower limit S _{L_F} and the first slip upper limit S _{U_F} ; when the first slip compensation value Slip _{COMP_F} is between the first slip lower limit S _{L_F} and the first slip upper limit S _{U_F} , the The linear relationship between the first slip compensation value Slip _{COMP_F} and the proportional ratio of the first feedforward voltage V _{FF_F can be determined.}

Please refer to FIG. 7 to display the data contained in the second comparison table. The details are as follows: from the acceleration signal 100 shown in FIG. 1 and the wheel speed signal of the left rear wheel 23 or the right rear wheel 24 The slip compensation value Slip _COMP calculated by 110 is defined as a second slip compensation value Slip _{COMP_R} , and the feedforward voltage V _FF corresponding to the left rear wheel 23 and the right rear wheel 24 is defined as a second Feed forward voltage V _{FF_R} . When the second slip compensation value Slip _{COMP_R} is equal to a second lower limit slip value S _{L_R} (for example, 10%), the second feedforward voltage V _{FF_R} corresponds to a second lower limit voltage V _{LV_R} (for example, 5V); When the second slip compensation value Slip _{COMP_R} is equal to a second upper limit of slip S _{U_R} (for example, 30%), the second feedforward voltage V _{FF_R} corresponds to a second upper limit voltage V _{UV_R} (for example, 10V); When Slip _{COMP_R} < S _{L_R} , the second feedforward voltage V _{FF_R} corresponds to 0V; when S _{L_R} < Slip _{COMP_R} < S _{U_R} , the second slip compensation value Slip _{COMP_R} and the second feedforward voltage V _{FF_R} have a proportional linear relationship to scale, and _{V LV_R <V FF_R <V UV_R} ; when _Slip COMP_R> S U_R time, the second feed-forward voltage _V FF_R corresponding to the first upper limit is equal to the voltage _V UV_R. Similarly, to avoid insufficient pressure relief, the upper limit voltage V _{UV_R} can be set to 10V.

In the embodiment of the present invention, after the parameter setting of the control module 13, the second comparison table includes the second lower limit voltage V _{LV_R} , the second upper limit voltage V _{UV_R} , and the second slip lower limit S _{L_R} and the second upper limit of slip S _{U_R} ; when the second slip compensation value Slip _{COMP_R} is between the second lower limit of slip S _{L_R} and the second upper limit of slip S _{U_R} , the The linear relationship between the second slip compensation value Slip _{COMP_R} and the proportional ratio of the second feedforward voltage V _{FF_R can be determined.}

Step S04: The control module 13 adds the basic control voltage V _{B to} the feedforward voltage V _FF to generate the brake control voltage V _P , which can be expressed as follows: V _P = V _B + V _FF

In the embodiment of the present invention, the brake control voltage V _P corresponding to each of the front wheels is defined as a first brake control voltage V _{P_F} , which can be expressed as follows: V _{P_F} = V _B + V _{FF_F}

The brake control voltage V _P corresponding to each of the rear wheels is defined as a second brake control voltage V _{P_R} , which can be expressed as follows: V _{P_R} = V _B + V _{FF_R}

In summary, the control module 13 outputs the first brake control voltage V _{P_F to} drive the proportional valve brake 120 of each of the front wheels (ie: the left front wheel 21 or the right front wheel 22), and outputs the second brake The control voltage V _{P_R} drives the proportional valve brake 120 of each of the rear wheels (ie, the left rear wheel 23 or the right rear wheel 24). Each of the brake control voltages V _{P_F} and V _{P_R} includes the components of each of the feedforward voltages V _{FF_F} and V _{FF_R} , and each of the feedforward voltages V _{FF_F} , V _{FF_R} is calculated from each of the slip compensation values Slip _{COMP_F} , Slip _{COMP_R} Come. In the following, referring to the actual measurement data of Figures 8A, 8B, 9A and 9B, although the wheel speed waveforms of each wheel are staggered or overlapped with each other, only by observing the wheel speed waveform trend of each wheel, we can still see that each of the feedforwards The effect of the voltages V _{FF_F} and V _{FF_R.}

Please refer to Figures 2, 8A and 8B, where the waveforms in Figures 8A and 8B are measured data of a first braking event, so the vehicle speed waveforms in Figures 8A and 8B are consistent, only the left front wheel 21 and The wheel speed waveform of the right front wheel 22 is shown in FIG. 8A, and the wheel speed waveforms of the left rear wheel 23 and the right rear wheel 24 are shown in FIG. 8B. In the first braking event, each of the braking control voltages V _{P_F} , V _{P_R does} not include each of the feedforward voltages V _{FF_F} and V _{FF_R} . As shown in Figures 8A and 8B, at about 6 seconds, the control module 13 intervenes in the braking system of the vehicle 20, so the speed of the vehicle 20 decreases from approximately 93 kilometers per hour with time. Please refer to Figure 8A. The amplitude of the wheel speed of the left front wheel 21 and the right front wheel 22 between 6.5 seconds and 7 seconds is relatively large, and the amplitude after about 7.2 seconds is relatively small; please refer to FIG. 8B, the left rear wheel 23 and the right rear wheel The amplitude of the wheel speed of the wheel 24 is greater than the amplitude of the left front wheel 21 and the right front wheel 22.

Please refer to Figure 2, Figure 9A and Figure 9B, where the waveforms of Figures 9A and 9B are measured data of a second braking event, so the vehicle speed waveforms of Figures 9A and 9B are consistent, only the left front wheel 21 and The wheel speed waveform of the right front wheel 22 is shown in FIG. 9A, and the wheel speed waveforms of the left rear wheel 23 and the right rear wheel 24 are shown in FIG. 9B. In the second braking event, each of the braking control voltages V _{P_F} V _{P_R} includes the feedforward voltages V _{FF_F} and V _{FF_R} ; it can be seen that the second braking event and the first braking event are two different braking events, and the braking control voltages used are different from each other. As shown in FIGS. 9A and 9B, at about 2.4 seconds, the control module 13 intervenes in the braking system of the vehicle 20, so the speed of the vehicle 20 decreases from about 97 kilometers per hour with time. Please refer to FIGS. 9A and 9B. 9B, the wheel speeds of the left front wheel 21, the right front wheel 22, the left rear wheel 23, and the right rear wheel 35 steadily decrease over time, especially as shown in FIG. 9A, the wheels of the left front wheel 21 and the right front wheel 22 The speed is almost the same.

Comparing the wheel speeds of Fig. 8A with Fig. 9A, Fig. 9A does not have the phenomenon of large amplitude between 6.5 seconds and 7 seconds as shown in Fig. 8A, so each of the feedforward voltages V _{FF_F} does improve the left front wheel 21 and the The wheel speed of the right front wheel 22 oscillates. Comparing FIG. 8B with FIG. 9B, the wheel speed amplitude of the left rear wheel 23 and the right rear wheel 24 of FIG. 9B is significantly reduced. In summary, for each wheel, the control module 13 of the present invention adds the basic control voltage V _{B to} the feedforward voltage V _FF to generate the brake control voltage V _P , so that each brake control voltage V _P includes the feedforward voltage V _FF , and the feedforward voltage V _FF assists in improving the wheel speed oscillation phenomenon of each wheel, so as to avoid the experience of intermittent rapid vibration in the car by the driver or passenger, and cause no discomfort Feel.

Please also refer to FIG. 6 and FIG. 7. In an example of the present invention, the second upper limit slip value S _{U_R} shown in FIG. 7 is lower than the first upper limit slip value S _{U_F shown in FIG.} When the left rear wheel 23 and the right rear wheel 24 are in a low slip state (for example, between 10% and 60%), the feedforward voltage V _{FF_R is} relatively high, so the left rear wheel 23 and the right rear wheel The pressure relief pressure of 24 is higher (that is, the braking pressure is lower). The reason why the present invention sets the second upper limit value of slip S _{U_R to} be lower than the first upper limit value of slip S _{U_F} is that, please refer to FIG. 2, FIG. 9A and FIG. 9B, compared with the left front wheel 21 and The right front wheel 22, when the left rear wheel 23 and the right rear wheel 24 are locked, the rear of the vehicle 20 may swing left and right. Therefore, the present invention _uses the setting of S _{U_R} < S U_F to make the left The braking pressure of the rear wheel 23 and the right rear wheel 24 is lower, which prevents the left rear wheel 23 and the right rear wheel 24 from being more likely to be locked due to higher braking pressure, which can effectively stabilize the body of the vehicle 20 and improve the A phenomenon in which the rear of the vehicle 20 sways left and right.

Claims (10)

An anti-lock braking system for a vehicle with multiple wheels. The anti-lock braking system includes: an accelerometer that outputs an acceleration signal, the acceleration signal reflects the acceleration of the vehicle; multiple wheel speedometers, respectively In response to the plural wheels of the vehicle, each wheel speed meter outputs a wheel speed signal, which reflects the wheel speed of each wheel; plural proportional valve brakes respectively correspond to the plural wheels of the vehicle, and each proportional valve brake respectively Receiving a braking control voltage, and adjusting a braking pressure of each wheel according to the magnitude of the braking control voltage; and a control module electrically connected to the accelerometer, the multiple wheel speedometer and the multiple proportional valve brake, the control After the module intervenes in a braking system of the vehicle, it generates the braking control voltage of each proportional valve brake according to the wheel speed signal of each wheel speedometer and the acceleration signal of the accelerometer; wherein, the control module is based on The wheel speed signal and the acceleration signal of each of the wheel speedometers calculate a slip feedback value, and generate a basic control voltage according to a slip deviation value between a slip target value and the slip feedback value; the control The module performs differential compensation on the slip feedback value to generate a slip compensation value, and corresponds the slip compensation value to a feedforward voltage in a table look-up manner; the control module adds the basic control voltage to the Feed forward voltage to generate the brake control voltage. The anti-lock braking system according to claim 1, wherein the control module stores a plurality of comparison tables for the control module to implement the table look-up method, and each comparison table includes a lower limit voltage, an upper limit voltage, and a The lower limit of slip and an upper limit of slip; when the slip compensation value is between the lower limit of slip and the upper limit of slip, the slip compensation value is proportional to the feedforward voltage The linear relationship. The anti-lock braking system according to claim 2, wherein the plurality of wheels includes a plurality of front wheels and a plurality of rear wheels, and the plurality of comparison tables include a first comparison table and a second comparison table, and the first comparison table compares The front wheels should be plural, and the second comparison table corresponds to the plural rear wheels; the upper limit value of the slip in the first comparison table is a first upper limit value of the slip, and the upper limit value of the slip in the second comparison table is Is a second upper limit of slip, and the second upper limit of slip is lower than the first upper limit of slip. The anti-lock braking system according to claim 3, wherein the slip feedback value (Slip _FB ) is expressed as follows:

In the above formula, V _{est is} the vehicle speed of the vehicle, and W is the wheel speed of each wheel calculated according to the wheel speed signal of each wheel speedometer. The anti-lock braking system according to claim 4, wherein the slip compensation value ( Slip _COMP ) is expressed as follows:

In the above formula, C is the weight, 0

C

1, and the C value is greater than the front wheel of the plurality of value C after the plurality of wheels. An anti-lock braking control method is executed after a control module intervenes in a braking system of a vehicle, the vehicle includes a plurality of wheels, and the anti-lock braking control method includes: receiving a wheel speed signal of each wheel of the vehicle And an acceleration signal; calculate a slip feedback value according to the wheel speed signal and the acceleration signal of the vehicle, and generate a basic control voltage according to a slip deviation value between a slip target value and the slip feedback value ; The slip feedback value is differentially compensated to generate a slip compensation value, and the slip compensation value corresponds to a feedforward voltage in a table look-up mode; the basic control voltage is added to the feedforward voltage to generate a Brake control voltage; and The brake control voltage is output to a proportional valve brake, and the proportional valve brake adjusts a brake pressure of each wheel according to the magnitude of the brake control voltage. The anti-lock braking control method according to claim 6, wherein the table look-up method uses a plurality of comparison tables, each of the comparison tables includes a lower limit voltage, an upper limit voltage, a lower limit of slip, and an upper limit of slip Limit; when the slip compensation value is between the lower limit of the slip and the upper limit of the slip, the slip compensation value and the feedforward voltage are proportional to the linear relationship. The anti-lock braking control method of claim 7, wherein the plurality of wheels includes a plurality of front wheels and a plurality of rear wheels, and the plurality of comparison tables include a first comparison table and a second comparison table, and the first comparison table Corresponding to the plural front wheels, the second comparison table corresponds to the plural rear wheels; the upper limit value of the slip of the first comparison table is a first upper limit of the slip, and the upper limit of the slip of the second comparison table is The value is a second upper limit of slip, and the second upper limit of slip is lower than the first upper limit of slip. The anti-lock braking control method according to claim 8, wherein the slip feedback value (Slip _FB ) is expressed as follows:

In the above formula, V _{est is} the vehicle speed of the vehicle, and W is the wheel speed of each wheel calculated according to the wheel speed signal of each wheel speedometer. The anti-lock braking control method according to claim 9, wherein the slip compensation value ( Slip _COMP ) is expressed as follows:

In the above formula, C is the weight, 0

C

1, and the C value is greater than the front wheel of the plurality of value C after the plurality of wheels.

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